The gene switch represents a major advance in gene therapy. In Phase I, we developed a gene switch for gene therapy that provides control over the level of expression of the therapeutic gene by oral administration of a safe drug. We demonstrated function of the gene switch in vivo in several tissues. In Phase II, we propose to work on the development of a non-viral gene medicine that provides controlled expression of growth hormone(GH) for the treatment of GH deficiency in children (short stature) as well wasting associated with chronic disease in adults. We have shown that gene medicines comprised of muscle-specific delivery and expressing systems can provide GH replacement for > l month after a single IM injection. We will develop a gene medicine that is administered by intramuscular injection, delivered to mature muscle cells using a polymer-based formulation, and expresses high levels of GH under control of the gene switch. The gene switch will allow more physiological, diurnal expression of GH which will enhance both the safety and efficacy of GH replacement. The goal of this project is to develop gene medicines to the point of proposing clinical trials. PROPOSED COMMERCIAL APPLICATION: Growth hormone (GH) is an important biological product for the treatment of GH deficiency (short stature) in children and wasting (cachexia) in adults. Worldwide sales of GH (protein) are >$500 M. There is a clinical need for improved products that provide more a more physiological pattern of gene expression, more prolonged duration of action, convenient administration, and reduced cost. The Total Available Market world wide is estimated to be approximately $1.15 billion. With conservative estimates for penetrance and pricing we estimate the market potential for a GH gene medicine to be >$500 M.